Axially compressive degradation picks and holders

ABSTRACT

A degradation pick or holder shank for facilitating installation, retention and removal is disclosed. The shank may comprise an axially compressive portion that may contract radially when stretched axially and then expand again radially when released. An installation tool may be used to stretch the shank axially during insertion into a bore and then release the shank to retain it within the bore.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of U.S. Provisional Application Ser. No. 62/240,932, filed Oct. 13, 2015, the disclosure of which is incorporated by reference.

BACKGROUND

Degradation picks are known to be used in such fields as road milling, mining, and trenching to engage and degrade tough materials such as asphalt, concrete, and rock. In use, such degradation picks may be secured to an exterior of a rotatable drum or continuous chain so as to be repeatedly brought into contact with a surface of a material to be degraded.

Degradation picks are known to take several forms. One form of degradation pick, as described in U.S. Pat. No. 7,396,086 to Hall, et al., comprises a shank attached to a base of a steel body. A cemented metal carbide core with an impact tip comprising a diamond material may be press fit into the steel body opposite the shank. The shank may be secured within a holder or block attached to a milling drum leaving the impact tip exposed.

Such degradation picks and holders may dislodge from their respective bore holes due to the repeated impact forces experienced while in use. Also, it is often necessary to replace degradation picks as they wear which can be a dangerous, time consuming and expensive process. Consequently, efforts have been made to provide more secure connections between degradation pick and holder shanks and bore holes that may also allow for quick removal and replacement.

For example, U.S. Pat. Pub. No. 2011/0254349 to Hall et al., describes a pick assembly comprising a pick shank configured to be press fit in a bore within a block. The shank comprises at least one longitudinal recess extending along the shank from a distal end of the shank. The recess allows the shank to resiliently collapse upon insertion into the bore while maintaining a press fit between the bore and the shank.

Despite these advancements in the art, designs such as these comprising uneven perimeter thicknesses may lead to uneven stresses and thus premature failure. Thus, improvements allowing for more secure connections between degradation pick or holder shanks and bore holes that also allow for quick removal and replacement and even perimeter thicknesses are desired.

SUMMARY

A degradation pick or holder shank for facilitating installation, retention and removal is disclosed. The shank may comprise an axially compressive portion that may contract radially when stretched axially and then expand again radially when released. An installation tool may be used to stretch the shank axially during insertion into a bore and then release the shank to retain it within the bore.

Such a shank may comprise at least one compliant region comprising an axially-variable cross section. The axially-variable cross section may comprise a bellows shape, an accordion shape, or other shapes to facilitate compliance. To form such a compliant region, a machining tool may be inserted to machine crevices into an interior of a shank.

A shank of a degradation pick or holder may be inserted into a bore disposed within a holder or block wherein an installation tool may pull a distal end of the shank further into the bore. Pulling the distal end further into the bore may cause axial expansion within the shank and radial contraction within the compliant region. When the installation tool is withdrawn, the compliant region may expand radially to secure the shank within the bore.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an embodiment of a formation degradation machine.

FIG. 2 illustrates a rotatable drum.

FIGS. 3a-3b illustrate a degradation pick, according to an embodiment of the invention.

FIG. 4a-4b illustrate a holder, according to an embodiment of the invention.

FIG. 5a-5b illustrate a perspective cross-sectional view of an embodiment of a holder.

FIG. 6a-d illustrates a perspective cross-sectional views of embodiments of a holder.

FIG. 7 illustrates a perspective cross-sectional views of embodiments of a holder.

FIG. 8 illustrates a perspective cross-sectional views of embodiments of a holder.

FIG. 9 illustrates a perspective partially cross-sectional view of another embodiment of a holder.

FIG. 10 illustrates a perspective cross-sectional view of embodiments of a portion of a holder.

FIG. 11a-11b illustrates a perspective cross-sectional views of embodiments of a compliant region.

FIG. 12a-c illustrates a perspective cross-sectional views of various embodiments of installation tools.

FIG. 13 illustrates a perspective cross-sectional view of an embodiment of a pick.

DETAILED DESCRIPTION

In the following detailed description, only certain example embodiments of the disclosed subject matter are shown and described, by way of illustration. As those skilled in the art would recognize, the disclosed subject matter may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Also, in the context of the present application, when a first element is referred to as being “on” a second element, it can be directly on the second element or be indirectly on the second element with one or more intervening elements interposed therebetween.

FIG. 1 shows an embodiment of a formation degradation machine 1000 comprising a plurality of degradation picks 1100 secured to an exterior of a rotatable drum 1200. Rotation of the rotatable drum 1200 by the formation degradation machine 1000 may bring the degradation picks 1100 repeadedly into contact with a surface of a material 1300. This repeated engagement of the degradation picks 1100 to the material 1300 may degrade the material 1300 causing it to break up into aggregate 1301. In the present embodiment, the formation degradation machine 1000 is located in an underground mine and the material 1300 to be degraded, coal for example, is contained in a wall of the mine. Once a portion of the material 1300 is degraded into aggregate 1301 it may be captured by a conveyor 1001 and removed for processing. While the embodiment shown depicts a rotatable drum 1200 on a formation degradation machine as part of a mining operation, it should be understood that the present invention may also be used in conjunction with rotatable drums or continuous chains being used in mining, road milling, trenching or other operations where it is desirable to degrade tough materials such as asphalt, concrete or rock.

FIG. 2 shows an embodiment of a rotatable drum 2200 as seen by a material to be degraded. A plurality of blocks 2201 may be disposed around an exterior of the rotatable drum 2200. Each of the blocks 2201 may have a bore disposed therein to receive a shaft 2101 from each of a plurality of degradation picks 2100. Rotation of the rotatable drum 2200 may cause the degradation picks 2100 to engage and degrade a material. The blocks 2201 may be positioned around the exterior of the rotatable drum 2200 to optimize degradation and/or transport aggregate away from the material being degraded.

FIG. 3a shows a perspective view of an embodiment of a degradation pick 3100 a and a pick block 3201 a. The degradation pick may comprise a shank 3101 a that may be inserted into a bore 3202 a of the pick block 3201 a.

FIG. 3b shows a perspective view of an embodiment of a degradation pick 3100 b, a holder 3400 b, and a pick block 3201 b. The pick block 3201 b may comprise a bore 3202 b for receiving a shaft 3401 b of the holder 3400 b. The holder 3400 b may comprise a hole 3402 b for receiving a shank 3101 b of the degradation pick 3100 b. Different holders may comprise bores of various diameters so as to accommodate degradation picks of various sizes to attach to a degradation drum (shown in FIG. 1).

FIG. 4a discloses a perspective view of an embodiment of a holder 100 a. The holder 100 a may comprise a body 101 a attached to a shank 111 a. The shank 111 a may comprise a compliant region 110 a with an axially-variable cross section. In the embodiment shown, the compliant region 110 a comprises a bellows shape. When the shank 111 a is urged into a bore (as shown in FIG. 3b ) the compliant region 110 a may radially compress facilitating entry into the bore.

FIG. 4b discloses a perspective cross-sectional view of another embodiment of a holder 100 b comprising a body 101 b and shank 111 b. A compliant region 110 b with a bellows shape may comprise a thin wall 112 b that may flex when subjected to radial or axial compression or expansion.

FIG. 5a discloses a perspective cross-sectional view of an embodiment of a holder 200 a and a block 220 a. The holder 200 a may comprise a shank 211 a with a compliant region 210 a shaped to fit within a bore 221 a of the block 220 a. A bellows shape of the compliant region 210 a may comprise a radius 212 a, wherein the radius 212 a may compress when urged into the bore 221 a. Due to a tapering 222 a of the bore 221 a, the radius 212 a may compress further when the holder 200 a is urged into the bore 221 a of the block 220 a, as shown in FIG. 5 b.

FIG. 5b discloses a perspective cross-sectional view of an embodiment of a holder 200 b inserted into a bore 221 b within a block 220 b. An internal radius of the bore 221 b may be narrower than an external radius 212 b of a compliant region 210 b of the holder 200 b when not disposed within the bore 221 b (as shown in FIG. 5a ). Thus the external radius 212 b of the compliant region 210 b may contract when urged into the bore 221 b. Contraction of the radius 212 b may cause the holder 200 b to elongate along a central axis 202 b thereof, enabling the holder 200 b to extend farther into the bore 221 b.

FIGS. 6a through 6d are perspective cross-sectional views of embodiments of holders comprising compliant regions of various geometries. For example, in the embodiment shown in FIG. 6a a holder 300 a has a compliant region 310 a comprising a pleat 313 a that creates additional surface area allowing for more axial expansion when inserted into a bore (shown in FIG. 5). In FIG. 6b , another embodiment of a compliant region 310 b comprises a sharp accordion shape 314 b with three pleats 315 b. Another embodiment shown in FIG. 6c comprises a compliant region 310 c comprising a smooth accordion shape 316 c comprising three pleats 315 c. In yet another embodiment, shown in FIG. 6d , a compliant region 310 d comprises a barbed shape 317 d comprising three pleats 315 d. Each of these various geometries may contribute to compliance.

FIG. 7 discloses a perspective cross-sectional view of an embodiment of a holder 400 comprising a shank 401 with a compliant region 410. The compliant region 410 may comprise a barbed shape 417 with one or more pleats 415. A distal end 402 of the shank 401 may comprise a threaded portion 403, wherein threaded components (shown in FIG. 9) for holder installation and removal may be utilized.

FIG. 8 discloses a perspective cross-sectional view of a holder 500 disposed in a bore 521 within a block 520. An installation tool 540, such as a bolt, may be inserted through a hole 504 in a front portion of the holder 500. The installation tool 540 may pass through a compliant region 510 and apply pressure to a barrier 505 on a distal end of a shank of the holder 500. The installation tool 540 may be pressed against the barrier 505 by, for example, a hammer (not shown), whereby the holder 500 may elongate axially while the compliant region 510 is compressed radially to facilitate installation. As the installation tool 540 is removed the holder 500 may retract axially while the compliant region 510 expands radially to facilitate retention of the holder 500 within the bore 521. To remove the holder 500 from the bore 521, pressure may again be applied to the barrier 505 by the installation tool 540 to radially constrict the compliant region 510 while the holder 500 is withdrawn.

FIG. 9 discloses a perspective partially cross-sectional view of another embodiment of a holder 600 disposed in a bore 621 within a block 620. An installation tool 640 with a threaded end 641 may be inserted through a hole 604 and a compliant region 610 of the holder 600 whereby the threaded end 641 may be secured to a threaded portion 603 at a distal end of the holder 600. In this configuration, the installation tool 640 may apply pressure against the threaded portion 603 which may radially constrict the compliant region 610 to facilitate installation. As the installation tool 640 is removed the compliant region 610 may radially expand to facilitate retention of the holder 600 within the bore 621. For removal, pressure may again be applied to the threaded portion 603 by the installation tool 640 while the holder 600 is withdrawn.

FIG. 10 discloses a perspective cross-sectional view of embodiments of a portion of a holder 700 comprising a compliant region juxtaposed with a portion of a holder 750 lacking a compliant region, both disposed in a bore within a block 720. As can be seen, the holder 700 comprising the compliant region may extend further into the block 720 than the holder 750 without the compliant region.

FIGS. 11a and 11b discloses perspective cross-sectional views of embodiments of a compliant region 810 a, 810 b comprising a sharp accordion shape 814 a, 814 b. To form an interior of the sharp accordion shape 814 a, 814 b, a machine tool 850 a, 850 b may be inserted into an opening 819 a, 819 b to machine an interior thereof.

FIGS. 12a through 12c disclose perspective cross-sectional views of various embodiments of installation tools. For example, FIG. 12a shows a holder 900 a disposed in a bore within a block 920 a. The holder 900 a may comprise a threaded portion 906 a disposed within the holder 900 a for receiving a threaded end of an installation tool 940 a. The installation tool 940 a may be inserted through a compliant region 910 a and into the threaded portion 906 a. In this configuration, the installation tool 940 a may axially compress the compliant region 910 a expanding it radially to help retain the holder 900 a within the block 920 a.

FIG. 12b shows a holder 900 b disposed in a bore within a block 920 b. The holder 900 b may comprise a threaded portion 906 b disposed within the holder 900 b mating with a threaded part of an installation tool 940 b. The installation tool 940 b may pass through the threaded portion 906 b and press against a barrier 905 b on a distal end of the holder 900 b causing a compliant region 910 b disposed between the threaded portion 906 b and barrier 905 b to expand axially. This axially expansion may radially constrict the compliant region aiding in installation or removal of the holder 900 b.

FIG. 12c shows a holder 900 c disposed in a bore within a block 920 c. The holder 900 c may comprise a hole 904 c running therethrough to a compliant region 907 c. An retention tool 940 c may be disposed in the hole 904 c and thread into a threaded portion 903 c disposed at a distal end of the holder 900 c. By so doing, the retention tool 940 c may axially compress the compliant region 907 c causing it to expand radially and aiding in retaining the holder 900 c within the block 920 c. In this embodiment, the retention tool 940 c may remain with the holder 900 c until removal.

FIG. 13 discloses a perspective cross-sectional view of a pick 4100 disposed directly in a bore within a block 4120 without the use of a holder. The pick 4100 may comprise a body 4101 attached to a shank 4160. The shank 4160 comprises a compliant region 4110 wherein axial and radial expansion or contraction may occur. The shank 4160 may further comprise a threaded hole 4106 disposed therein for receiving an installation tool 4140. The installation tool 4140 may be inserted through the compliant region 4110 and into the threaded hole 4106 and may axially compress the compliant region 4110 causing it to expand radially to aid in retaining the pick 4100. Alternatively, unthreading the installation tool 4140 may allow the compliant region to axially expand and radially contract allowing for removal of the pick 4100.

Although only a few example embodiments have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the example embodiments without materially departing from the subject matter of this disclosure. Accordingly, all such modifications are intended to be included within the scope of this disclosure as defined in the following claims. Throughout the text and claims, use of the word “about” reflects the penumbra of variation associated with measurement, significant figures, and interchangeability, all as understood by a person having ordinary skill in the art to which this disclosure pertains. Additionally, throughout this disclosure and the accompanying claims, it is understood that even those ranges that may not use the term “about” to describe the high and low values are also implicitly modified by that term, unless otherwise specified. 

1. A degradation pick, comprising: an axially compressive region.
 2. The degradation pick of claim 1, wherein the axially compliant region comprises an axially-variable cross section.
 3. The degradation pick of claim 2, wherein the axially-variable cross section comprises a bellows shape.
 4. The degradation pick of claim 2, wherein the axially-variable cross section comprises an accordion shape.
 5. The degradation pick of claim 1, wherein when the axially compressive portion contracts radially when extended axially, and wherein the axially compressive portion expands radially when contracted axially. 